1. Field of the Invention
This invention relates to a method for producing a friction-modifying fuel or lubricant additive composition that contains a decreased level of reactant components.
2. Description of Related Art
Fuel economy standards mandated by the federal government have resulted in efforts by the automotive industry to improve the fuel economy of motor vehicles. One way to reduce fuel consumption is by reducing friction in particular areas of the engine, e.g., bearings, valve trains, pistons, rings, water and oil pumps. A moderate decrease in the friction of these components will be reflected in a corresponding fuel economy improvement. Therefore, there has been an ongoing search for friction modifier compositions that will decrease friction in these key areas and thus improve fuel economy.
Various types of additives have been used as friction modifiers. Some of the more commercially and conventionally used friction modifiers are fatty acid esters, fatty acid amides and fatty acid ester-amides. U.S. Pat. No. 4,960,530 discloses an example of a lubricant additive and composition that can reduce friction.
Hydroxyalkyl amides have been used extensively as friction modifiers. U.S. Pat. No. 4,729,769 discloses a fatty acid amide detergency additive which is the reaction product of a C6-C20 fatty acid ester and a mono- or di-(hydroxy hydrocarbonyl) amine.
U.S. Pat. No. 4,208,293 discloses a lubricating oil adapted for use as a crankcase lubricant in internal combustion engines containing a friction-reducing amount of a fatty acid amide or ester of diethanolamine.
Although the production of hydroxyalkyl amides as friction modifiers for fuel additives amongst other things has been quite extensive, most of processes for producing hydroxyalkyl amides produce a composition that retains a certain percentage of unreacted alkanolamine, together with other undesirable residuals. Certain end-use users desire hydroxyalkyl amides as friction modifying fuel additives with a decreased level and/or an undetectable level of alkanolamine and/or residual catalyst. Therefore, it would be advantageous to provide a process for producing hydroxyalkyl amides with a low level or an undetectable level of alkanolamine and/or residual catalyst.
The most common and simplest method of purifying hydroxyalkyl amides is through aqueous washes and the successive removal of the aqueous phase which results from the separation of the mixture into an organic and aqueous phase.
Typically, aqueous washes of hydroxyalkyl amide compositions result in low degrees of impurity removal while at the same time create an undesirable amount of waste water. In addition, aqueous washes can result in a decreased level of aqueous phase separation. It is important to have as great a level of aqueous phase separation as possible and therefore as little retained water in the organic phase because at high levels of retained water, more impurities are retained in the organic phase, more energy is required to dry the product due to the increased mass of water to be removed, foaming of the product results during the drying step and more aqueous waste is generated.
Therefore, it would be advantageous to provide a method for purifying hydroxyalkyl amide through use of an aqueous wash that would avoid the above-described problems and yet still provide for good separation of the organic and aqueous phases.